Aircraft ground support air conditioning unit with heat exchanger bypass

Abstract

A system and method of supplying temperature-controlled air to an aircraft environmental control system during ground support operations that uses a bypass valve in a bypass line to control the amount of cooling air flowing through a heat exchanger. The heat exchanger removes heat from a flow of compressed air supplied to the air conditioning unit and supplies cooled compressed air at a desired temperature. The temperature of the cooled compressed air is controlled by selectively positioning the bypass valve, which regulates cooling air flow through the heat exchanger.

I claim:  
     
       1. A temperature-controlled air supply system for use with a compressed air source and for connection to an aircraft on the ground, the air supply system comprising: 
       a primary air flow passage coupled to receive a flow of primary air form a single primary air source;  
       a bypass flow passage fluidly coupled in parallel with the primary air flow passage;  
       a first heat exchanger having at least a first fluid flow path and a second fluid flow path, the first fluid flow path fluidly coupled in series in the primary air flow passage, the second fluid flow path coupled to receive a flow of compressed air from the compressed air source, the first heat exchanger adapted to transfer heat between the primary air and the compressed air and supply at least conditioned compressed air; and  
       a bypass valve mounted on the bypass flow passage and selectively moveable between a closed and an open position to control primary air flow rate through the bypass flow passage, whereby primary air flow rate through the first heat exchanger is controlled to thereby control conditioned compressed air temperature.  
     
     
       2. The system of  claim 1 , further comprising: 
       a temperature sensor mounted downstream of the first heat exchanger second fluid flow path and operable to supply a temperature signal representative of the conditioned compressed air;  
       a controller coupled to receive the temperature signal from the temperature sensor and operable, in response thereto, to supply a valve control signal; and  
       a valve operator coupled to receive the valve control signal and operable, in response thereto, to selectively move the bypass valve to control primary air flow rate through the bypass flow passage.  
     
     
       3. The system of  claim 1 , further comprising: 
       at least one cooling turbine having an air intake port and an air exhaust port;  
       a second heat exchanger coupled to receive the conditioned compressed air from the first heat exchanger and turbine exhaust air from the cooling turbine air exhaust port, and adapted to transfer heat from the conditioned compressed air to the cooled air exhausted from the cooling turbine and supply warmed turbine exhaust air and further conditioned compressed air.  
     
     
       4. The system of  claim 3 , wherein the cooling turbine air stake is coupled to receive the further conditioned compressed air from the second heat exchanger. 
     
     
       5. The system of  claim 4 , further comprising: 
       a moisture separator coupled between the second heat exchanger and the cooling turbine air intake.  
     
     
       6. The system of  claim 1 , further comprising: 
       a fan operable to draw the primary air from a primary air source into the primary air flow passage.  
     
     
       7. The system of  claim 6 , wherein the fan is further operable to draw the primary air into the bypass flow passage. 
     
     
       8. The system of  claim 6 , wherein the fan is configured to pull the primary air through the first heat exchanger. 
     
     
       9. The system of  claim 6 , wherein the fan is configured to push the primary air through the first heat exchanger. 
     
     
       10. The system of  claim 1 , wherein the primary air is ambient air. 
     
     
       11. The system of  claim 1 , wherein the compressed air source is an auxiliary power unit (APU). 
     
     
       12. The system of  claim 1 , wherein the compressed air source is a diesel engine driven compressor. 
     
     
       13. A method of conditioning compressed air supplied from an aircraft ground support equipment, the method comprising: 
       supplying a flow of compressed air through a first heat flow path in a heat exchanger;  
       supplying a flow of primary air from a single source through a second flow path in the heat exchanger to thereby condition the compressed air to a temperature; and  
       selectively diverting a portion of the primary air away from the second heat exchanger flow path to control primary air flow rate through the second heat exchanger flow path, whereby the temperature of the conditioned compressed air exiting the heat exchanger is controlled.  
     
     
       14. The method of  claim 13 , further comprising: 
       flowing the conditioned compressed air through a second heat exchanger; and  
       flowing turbine exhaust air through the second heat exchanger to thereby further cool the cooled compressed air and warm the turbine exhaust air.  
     
     
       15. The method of  claim 14 , further comprising: 
       supplying the warmed turbine exhaust air as the temper controlled air to the aircraft.  
     
     
       16. The method of  claim 14 , further comprising: 
       flowing the further cooled compressed air into an air intake of the cooling turbine.  
     
     
       17. The method of  claim 13 , further comprising: 
       supplying the primary air from ambient surroundings.  
     
     
       18. The method of  claim 13 , further comprising: 
       supplying the compressed air from an auxiliary power unit (APU).  
     
     
       19. A temperature-controlled air supply system for use with a compressed air source and for connection to an aircraft on the ground, the air supply system comprising; 
       a primary air flow passage coupled to receive a flow of primary air;  
       a bypass flow passage fluidly coupled in parallel with the primary air flow passage;  
       a first heat exchanger having at least a first fluid flow path and a second fluid flow path, the first fluid flow path fluidly coupled in series in the primary air flow passage, the second fluid flow path coupled to receive a flow of compressed air from the compressed air source, the first heat exchanger adapted to transfer heat between the primary air and the compressed air and supply at least conditioned compressed air;  
       a bypass valve mounted on the bypass flow passage and selectively moveable between a closed and an open position to control primary air flow rate trough the bypass flow passage, whereby pay air flow rate trough the first heat exchanger is controlled to thereby control conditioned compressed air temperature;  
       a second beat exchanger coupled to receive the conditioned compressed air from the first heat exchanger and turbine exhaust air from a cooling turbine, and adapted to transfer heat from the conditioned compressed air to the turbine exhaust air and supply warmed turbine exhaust air and further conditioned compressed air;  
       at least one cooling turbine having an air intake in fluid communication with the second heat exchanger to receive therefrom the firer conditioned compressed air and an air exhaust in fluid communication with the second heat exchanger to supply thereto the turbine exhaust air;  
       a moisture separator coupled between the second heat exchanger and the cooling turbine air intake;  
       a fan operable to draw the primary air from the primary air source into the primary air flow passage;  
       a temperature sensor mounted downstream of the first heat exchanger second fluid flow path and operable to supply a temperature signal representative of the conditioned compressed air;  
       a controller coupled to receive the temperature signal from the temperature sensor and operable, in response thereto, to supply a valve control signal; and  
       a valve operator coupled to receive the valve control signal and operable, in response thereto, to selectively move the bypass valve to control primary air flow rate through the bypass flow passage.